It’s hard to avoid the legions of custom markup systems out there these days. Every Wiki has it’s own syntactical quirks, while packages like Markdown, Textile, BBCode (in dozens of variants), reStructuredText offer easy ways of hooking markup conversion in to existing applications. When it comes to being totally over-implemented and infuratingly inconsistent, markup systems are rapidly catching up with template packages. Never one to miss out on an opportunity to reinvent the wheel, I’ve worked on several of each ;)